Male-pattern baldness is usually inherited and also affects women. It's caused by oversensitive hair follicles. Dihydrotestosterone (DHT) is produced by the male hormone testosterone, and it causes the follicles to shrink and eventually stop functioning.

The involvement of testosterone in balding has led to the myth that going bald is a sign of virility. But men with male-pattern baldness don’t have more male hormones than other men. Their hair follicles are simply more sensitive to the hormones.

Receding hairline

Male-pattern baldness is so called because it tends to follow a set pattern. The first stage is usually a receding hairline, followed by thinning of the hair on the crown and temples.

When these two areas meet in the middle, it leaves a horseshoe shape of hair around the back and sides of the head. Eventually, some men go completely bald.

Male-pattern baldness is not a disease, so it won’t affect your health. However, if it’s causing you distress, consult your GP to get a diagnosis.

Your GP can refer you to a dermatologist for further analysis and, if necessary, to a psychologist to help with the trauma of hair loss.

If you have inherited the genes responsible for male-pattern or female-pattern baldness there's little you can do to prevent it from happening.

Treatments can slow down the process, but there’s no cure. The two most effective treatments for male-pattern baldness (also called androgenetic alopecia) are minoxidil and finasteride. Other treatments for hair loss include wigs, hair transplants and plastic surgery procedures, such as scalp reduction.

As a general rule, it's easier to maintain existing hair than to regrow it, and once the hair follicle has stopped working it cannot be revived.

"Start by talking to your GP, who can then refer you to a specialist NHS consultant," says Dr David Fenton, a consultant dermatologist at St John's Institute of Dermatology at St Thomas' Hospital in London.